1. Field of the Invention
The present invention generally relates to antenna units, and more particularly, to an antenna unit used in a radio communication system utilizing radio waves of extremely high frequency (EHF) such as a subscriber radio system and a cell radio system. In terms of structure, the present invention relates to a radio transmitter-receiver unit, i.e., an antenna unit having a structure in which an antenna integral-type radio transmitter-receiver apparatus is fixed to a peripheral surface of a strut.
2. Description of the Related Art
Recently, demands such as a reduction of production cost by decreasing a number of construction parts have been increasing for an antenna unit.
In general, an antenna unit is set up by carrying out azimuth adjustment and elevation adjustment in relation to another antenna unit for communicating therewith. Therefore, it is required for an antenna unit that it is capable of being adjusted using azimuth adjustment and elevation adjustment with a reduced number of construction parts.
FIGS. 1 and 2 both show an example of a conventional antenna unit 10. The antenna unit 10 has a supporting arm 12 extending horizontally from and fixed to a strut 11, an azimuth-elevation adjustment portion 13 located on one end of the supporting arm 12 and an antenna integral-type radio transmitter-receiver apparatus 14 fixed to the azimuth-elevation adjustment portion 13.
The azimuth-elevation adjustment portion 13 is comprised of a base mount 20 fixed on the supporting arm 12, a first mount 21 mounted on the base mount 20 and fixed, by screws, onto an arbitrary position in a direction indicated by the arrow A (the rotary direction of the base mount 20 around the perpendicular central axis 20a), a second mount 22 supported by a shaft 23 located on the side of the first mount 21 and fixed, by screws, onto an arbitrary position in a direction indicated by the arrow E (the rotary direction of the shaft 23 which is horizontal), and an elevation adjustment mechanism 24 located between the first mount 21 and the second mount 22.
The antenna integral-type radio transmitter-receiver apparatus 14 has a structure in which an antenna 30 is fixed to a radio transmitter-receiver 31. Besides the antenna 30 and the radio transmitter-receiver 31, the antenna integral-type radio transmitter-receiver apparatus 14 has a radome 32, an awning cover 33 and a fixing metal member 34.
The antenna integral-type radio transmitter-receiver apparatus 14 is fixed to the second mount 22 by fixing the fixing metal member 34 to the second mount 22.
The azimuth adjustment of the antenna unit 10 is carried out by appropriately moving the position of the screw of the first mount 21 in the direction indicated by the arrow A so that the antenna integral-type radio transmitter-receiver apparatus 14 is properly moved to a position around the perpendicular central axis 20a. The elevation adjustment of the antenna unit 10 is carried out by appropriately moving the position of the second mount 22 in the direction indicated by the arrow E shown in FIG. 4 so that the antenna integral-type radio transmitter-receiver apparatus 14 is properly moved to a position around the horizontal shaft 23.